Fast five-stage photomultiplier with GaP(Cs) dynodes

The use of negative-electron-affinity materials as secondary emitters results in marked performance improvements in photomultiplier detectors. This paper treats the developmental type C31024 photomultiplier which utilizes five GaP(Cs) dynodes to provide gains of the order of . The high secondary emission ratio (greater than 20) of the GaP(Cs) dynodes permits the electron-multiplier section of the device to resolve photoelectron inputs consisting ot 1, 2, 3 or 4 electrons as discrete events. The single-electron anode pulse rise time is 800 ps. Data are presented on time- and frequency- domain measurements and a comparison of measurement techniques is presented. Applications are discussed in the fields of laser-light detection and medical electronics.